Synthesis of polymeric emulsifiers based on ketoaldehyde resin and their application in emulsifying styrene/water two-phase system

摘要

Though the stabilization effect of polymeric emulsifiers onto emulsions is worse than that of small molecular emulsifiers, the application of polymeric emulsifiers can avoid small molecule residues in polymer products. Herein, a series of polymeric emulsifiers (M-CFR-x-K Na/M-MeCFR-x-K) are synthesized based on cyclohexanone formaldehyde resin (CFR)/methylcyclohexanone formaldehyde resin (MeCFR), which are firstly modified by maleic anhydride and then neutralized by bases. The effect of different counter ions, terminal groups and chain lengths on emulsion (styrene/water) property is studied by monitoring the stability and droplet size distribution of the emulsions. The results indicate that the emulsifier with KOH as neutralizer has better emulsifying performance than that with NaOH. Besides, the emulsion prepared by M-MeCFR-1.20-K, which has a hydrophilic group just at one end is more stable than that of M-CFR-2.25-K, which both ends are hydrophilic groups. The chain length of polymeric emulsifiers affects the stability of emulsions. And when the acid value is 1.91 mmol/g, the modified resin (M-CFR-2.25-K) has the best emulsifying performance. Furthermore, M-CFR-2.25-K (acid value:1.91 mmol/g) is used for emulsion polymerization. And after the reaction, polystyrene particulates can be directly obtained by precipitation without special demulsification procedure.